Amino-functional polysiloxanes are widely used in the textile industry as fibre lubricants and as fabric softeners and anti-wrinkle agents, and are also used in the personal care industry as hair conditioners and in skin care compositions.
Amino-functional polysiloxanes can be prepared by mixing a catalyst comprising both (i) at least one compound selected from barium hydroxide and strontium hydroxide and (ii) at least one compound selected from borates and phosphates of sodium with a silanol terminated organopolysiloxane compound and an organosilicon compound having at least one silicon-bonded alkoxy or alkoxyalkoxy group and an aminoalkyl group and reacting at a temperature of at least 50° C., as described in U.S. Pat. No. 5,391,675. This process is effective in preparing the amino-functional polysiloxane but requires an intensive filtration step to remove catalyst residues. Residual barium is often present in materials made via this route due to complexation with amine functionality. This may be detrimental in certain applications.
U.S. Pat. No. 5,344,906 describes a process for the production of an organosilicon condensation product which comprises contacting an organosilicon compound having at least one silanol group and wherein the silicon-bonded organic substituents can be hydrocarbon groups optionally substituted by amino, halogen, mercapto, hydroxyl, amido or ester substituents, with a quaternary ammonium phosphate, borate, carbonate or silicate.
U.S. Pat. No. 4,633,002 describes a process for the preparation of an aminofunctional organosilicone compound comprising reacting a silanol-terminated organosilicone compound with an aminofunctional silane compound in the presence of a catalytic amount of an organometallic compound.
WO-A-99/06486 and US-B-6284860 describe preparation of amino-functional polysiloxanes by reacting an organopolysiloxane with OH end groups with an alkoxysilane which contains at least one secondary or tertiary amine group in the presence of a Bronstedt or Lewis acid. The Bronstedt or Lewis acid, which is preferably an acidic phosphoric ester, but can be an inorganic acid or a sulphonic or carboxylic acid, is used in equivalent amount or a slight excess based on OH groups of the OH-terminated organopolysiloxane, and the alkoxysilane is added in stoichiometric excess based on the OH-terminated organopolysiloxane.